A number of procedures are known for the treatment of obstructive nephropathies, that is to say that type of condition that results in obstructed flow of use from the kidney to the outside, due to tumours or other causes.
These can be divided into surgical and interventional procedures. The former consist of forming an external aperture for the ureter, or for the ureters in the case of bilateral obstruction, through a vast range of surgical procedures; either directly (cutaneous ureterostomy) or by means of variously used bowel loops. The latter, on the other hand, make use of catheters which, by different routes, can be inserted percutaneously directly into the kidney (nephrostomic catheters), inducing drainage of the urine to the outside, or into the ureter (ureteral stent) passing through the stenotic area and re-establishing the communication between the portion upstream and downstream of the obstruction, thus allowing urinary outflow. Nephrostomic catheters are connected to urine collection bags worn on the outside of the patient's body that are emptied when they are fill. These bags are made of plastic material, for example PVC, and are substantially rectangular in shape, with a tube for connection to the nephrostomic catheter and in some cases also an emptying tube.
Nephrostomic catheters have the drawback of requiring maintenance and medication at the fixing point. Moreover, the fixing system through suturing to the skin or by self-anchoring means forming part of the catheter, often loosens allowing the catheter to become dislodged. Moreover, the presence of the urine collection bag causes inconvenience to the patient, besides causing a feeling of disability in patients already psychologically tried by a long illness.
Ureteral stents overcome the above problems but require that it be possible to pass the obstruction, something which cannot always be done.
The aim of the present invention is to overcome the practical and psychological drawbacks due to the need to wear an external urine collection bag. A further aim is to provide a prosthesis that can be worn by the patient for a long time without problems.
Another aim is to allow the contents of the prosthesis to be emptied easily. Yet another aim is to provide a prosthesis many parts of which can be easily dismantled for cleaning and sterilisation and which allows easy access to the other parts, for example to nephrostomic catheters, for cleaning.
Said drawbacks have been overcome by means of an assembly comprising a bag element, at least one type of band material and a valve element.
The prosthesis herein described has been conceived to replace the natural bladder in its role as a reservoir and in controlling discharge of accumulated fluid.
The bladder prosthesis is made of strong elastic material, is shaped so as to be accommodated in the median hypogastric region, in a subcutaneous, prefascial site or pocket where it is positioned after incising the skin along the subumbilical transiliac line and then freeing the integuments down to the suprapubic region.
The shape is roughly comparable to a rectangle with two corners, those belonging to one of the longer sides, strongly radiused.
This longer side forms the bottom part of the bladder whilst the opposite side is intended to be anchored to the muscle fascia initially by suturing and subsequently by incorporation into the reactive fibrous tissue of a biocompatible material fixed to the bag for this purpose. The bladder is preferably a thin silicone bag obtained by spraying on a model silicone material dispersed in solvent then evaporated, and then curing in a high-temperature oven; or by dipping/brushing a model into/with silicone material dispersed in solvent.
The silicone bag could be obtained by whichever other known way apt for generating an opportune thickness of the biocompatible and elastic material.
A silicone-metal-plastic structure is applied in the central part of the lower side, constituting the inlet and outlet valve of said bladder. Two lengths of silicone tube for connection with the ends of two nephrostomic catheters converge on this structure. Under the pressure of the fluid coming from the catheters, the valve opens so that the urine can flow into the bladder. Emptying of the bladder takes place through said valve.
This arrangement makes it possible to optimise the maximum size of the discharge outlet and at the same time the minimum pressure for opening of the valve for filling.
Lastly a plug provided with a gasket ensures tight closure of the bladder throughout the day.
The valve that is described also serves to stop fluid pressure waves, pulsed or otherwise, from the bladder towards the kidneys. In fact any reflux that might occur from the bladder to the kidneys through the nephrostomic catheters because of a defective valve seal would create a pressure wave that would oppose the hydrostatic filtering pressure of the urine, and would therefore injure the kidneys structures capable to secrete urine.